This set of Drug Biotechnology Multiple Choice Questions & Answers (MCQs) focuses on “Mechanisms of Drug Absorption”.
1. Which is the major process of absorption for more than 90% of drugs?
a) Facilitated diffusion
b) Active transport
c) Endocytosis
d) Passive diffusion
View Answer
Explanation: Passive diffusion is also known as non-ionic diffusion. It is the major process through which 90% of the drugs get absorbed. The driving force for passive diffusion is the concentration gradient and electrochemical gradient.
2. What is the driving force for Passive Diffusion?
a) Concentration gradient only
b) Electrochemical gradient only
c) Charge equilibration and concentration gradient
d) Concentration and Electrochemical gradient both
View Answer
Explanation: Passive diffusion, the driving forces are both concentration gradient and electrochemical gradient. According to Fick’s first law of diffusion, drug molecules always diffuse from the site of higher concentration to the site of lower concentration until equilibrium is attained.
3. Which kind of molecules cannot pass through a pore transport?
a) Low Molecular weight molecules
b) Water-soluble drugs
c) Molecules up to 400 Dalton
d) Molecules greater than 400 Dalton
View Answer
Explanation: Pore transport is important for the absorption of low molecular weight and size molecules. Water-soluble drugs can also easily pass through the aqueous filled spaces or pores in the cell membrane. Linear molecules of size up to 400 Dalton can be absorbed.
4. What is the driving force of Pore Transport?
a) Hydrostatic pressure
b) Concertation Gradient
c) Electrochemical gradient
d) Charge equilibration
View Answer
Explanation: The driving force of pore transport is Hydrostatic pressure and Osmotic pressure across the cell membrane. Electrochemical gradient and concentration gradient is the driving force of passive diffusion.
5. What will be the best definition for “carrier”?
a) Nonpolar drugs can be transported through carrier-mediated transport
b) Carrier binds reversibly and no covalently with the molecules
c) It discharges the molecules and gets destroyed itself
d) The carrier is a protein
View Answer
Explanation: The carrier-solute complex can cross the membrane to reach the other site where the carrier discharges the solute and returns back to its position. The carriers carry polar charged molecules and are mostly enzymes.
6. What is the major difference between Facilitated diffusion and Passive diffusion?
a) Carrier-mediated transport
b) Downhill transport
c) Energy is used
d) Inhibition by metabolic poisons
View Answer
Explanation: Facilitated diffusion is a carrier-mediated transport which operates down the concentration gradient. It is faster than passive diffusion because of the involvement of Carriers. The driving force is the concentration gradient.
7. What influences the permeation of drugs in an Ionic or Electrochemical diffusion?
a) Charge on the membrane
b) Charge on the particle
c) Concentration gradient
d) Equilibration of charge
View Answer
Explanation: The charge on the membrane influences the permeation of drugs. The permeation of positively charged drugs depends on the potential difference or electrical gradient as the driving force across the membrane.
8. Which kind of drugs are absorbed through endocytosis?
a) Molecular weight ranging 100-400Dalton
b) Water-soluble drugs
c) Macromolecular drugs or drugs as oily droplets
d) Polar drugs
View Answer
Explanation: Macromolecular drugs, Drugs as solid particles and drugs as oily particles are absorbed through endocytosis. Passive diffusion helps in the absorption of drugs with molecular size fro 100-400 Dalton.
9. Which drugs are absorbed through pore transport?
a) High lipophilicity
b) Water-soluble drugs of molecular weight less than 100 Dalton
c) Oily droplets
d) Affinity for carriers
View Answer
Explanation: Pore transport helps in the transport of water-soluble drugs which are of molecular weight less than 100 Dalton. Drugs with high lipophilicity and a molecular weight between 100-400 Dalton are transported by Passive diffusion.
10. Which types of drugs get absorbed by ion-pair transport?
a) High lipophilicity
b) Oily droplets
c) Affinity for carriers
d) Drugs that ionize at all pH conditions
View Answer
Explanation: Ion-Pair Transport is the mechanism where absorption of drugs like quaternary ammonium compounds, sulphonic acids get absorbed. These drugs can get ionize at all pH conditions. These neutral complexes have lipophilicity and aqueous solubility for passive diffusion.
11. Which of these absorption methods involves engulfing of the extracellular drug?
a) Endocytosis
b) Passive diffusion
c) Facilitated diffusion
d) Ion-Pair transport
View Answer
Explanation: Endocytosis is the absorption method which includes engulfing of extracellular materials within a segment of the cell membrane to form a saccule or vesicle which will be then pinched off intracellularly.
12. Which is the other name of “cell eating”?
a) Transcytosis
b) Phagocytosis
c) Pinocytosis
d) Endocytosis
View Answer
Explanation: Phagocytosis is a type of endocytosis. Phagocytosis is also called cell eating which includes absorption of solid particulates. Endocytosis is of two types phagocytosis and pinocytosis later meaning cell drinking.
13. Transfer of an endocytic vesicle from one extracellular compartment to another is known as _____________
a) Phagocytosis
b) Transcytosis
c) Pinocytosis
d) Endocytosis
View Answer
Explanation: Transfer of an endocytic vesicle from one extracellular compartment to another is known as Transcytosis. Phagocytosis is the engulfing of solid particulates. Pinocytosis is the absorption of fluids.
14. A drug can be absorbed by more than one mechanism.
a) True
b) False
View Answer
Explanation: Yes, a drug can be absorbed by different mechanisms through different sites in the body. The mechanism depends upon the absorption site of the body. A drug can be absorbed passively and actively.
15. Which kind of absorption mechanism is showing in the following picture?
a) Endocytosis
b) Passive transport
c) Active transport
d) Facilitated diffusion
View Answer
Explanation: Passive diffusion is a kind absorption where substances move from higher concentration to the lower concentration without the use of any carriers or energy. 90% of the drugs are absorbed through Passive diffusion.
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